Improvement in land conveyance



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Letters Patent No. 64,134, dated April 23, 1867.

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TO ALL WHOM IT MAY CONCERN:

Be it known that I, R. J. NUNN, of Savannah, in the county of Chatham, and State-ot` Georgia, have invented anew and useful Improvement'in Land Conveyanceg and I do hereby declare that the following is a full, clear, and exact description thereof, which will enable others skilled iu the' art to make and use thc same, reference being had to the accompanying drawings, forming part of this specification.

' Figure I is a plan or top view; and

Figure 2, a side elevation` Similar letters of reference indicate like parts.

A A, in the drawings, represent frames, which at each end are rounded with a curve equal to their height This frame A is supported upon a series of grooved friction-rollers, B B, each of which series rests upon and is surrounded by a flexible band, C, equal in width. to ,the length of the rollers, the whole surface of which bands, between the points D and E, rests upon the ground between the ground and the friction-rollers, the rollers projecting from the frames suiciently to prevent the contact of the frames and bands. These bands are ribbed, which ribs catch in the grooves of the rollers. Motion is communicated tothe bands C at thepoint F by means of the driving-wheel G, the friction of the band on the periphery of the wheel being increased by the pressure of two rollers, H H, susceptible of adjustment by set-screws I I. J is the steam boiler; K, the steam cylinder, having piston; L, the connecting-rod, and M a cock in the steam pipe N to regulate the speed by varying the supply of steam. The friction-rollers and the driving-wheel are grooved to accommodate the projection or rib of the band, the purpose of this projection being to serve the purpose of a guide and to prevent the-band from slipping ofi` of the rollers. The bands may be made of wrought steel, flat chain, and the projections or ribs of' fine steel wire interlocked with or wrought in the chain-work of the band. In the drawing only one application of the principle of the pulley to land conveyance is illustrated, butit is obvious that thc methods of application admit of many variations; for example, the rope or rib used for a guide to the band may be replaced with cogs or teeth worked in the band, and would answer the double purpose of guides to prevent the band from slipping out ouf-place, and to increase the friction on the driving-wheel, which could be correspondingly cog/ged or toothed in its groove, or the teeth could be made on the rollers and driving-wheel and the band be made with slots or cavities for the Vteeth to mesh in, or there may be other guides at the sides to keep the band in place. The Inumber of bands maybe more or less, and also the number, form,V and size of the frictionrollers maybe varied, as well also as the position, size, and number of the driving-wheels, and the manner of communicating power and producing motion in the band; still the principle of operation will be the same. In order toguide the machine it is only necessary to vary the velocity ofone band `with regard to the other, and if a double-cylinder steam engine is the power employed this may be done by operating the throttle-valve of one or the other side, according to thedirection in which the machine is to move. If, however, a single cylinder is the motor some suitable mechanism, such as cone-pulleys, gears, etc., may he employed.

The advantages claimed for a machine onv this principle are:

First. By the increase of bearing surface the pressure per square inch upon the ground can be reduced far below that exerted by a man; as, for example, suppose the square inches of the sole of a mans foot to be-twentyf five (25) and the average of weight to be one hundred and twenty-tive (125) pounds; this would give a pressure per square inch of five pounds. Now, if the bands of the machine be one (1) foot wide and the length of each band in contact with the ground be fifteen (15) feet, that would give abearing surface of thirty square feet or four thousand three hundred and twenty square inches, which, with a pressure of five (5) pounds to the square inch would sustain twenty-one thousand six hundred pounds. Thus a machine constructed in these proportions coulll carry over twenty thousand pounds (including its own Wight) and not bear as heavily on the ground as a man of ordinary weight, and could consequently carry half that weight over ground too soft to support the weight of a man.

Second. There is no possibility of slip. If the bands move at all the machine must move also, because so long as the friction between the bands and the ground is greater than between the bands and the machine the movement of the machine is insured; and while it is true that by adding weight to the machine the friction between it and the bands is increased, that is, the friction on the axles of the rollers, the friction of the bands on the ground is increased also. und the relative proportion of the friction remains unchanged. The engine muy stall by the resistance oi' the friction between the bands and the machine becoming greater than its power to overcome, which of course depends on the power of the engine und the weight to be carried, but the machine cu-nnot slip.

Third. The niuchine cnnnof be slid over the ground, for, to a force exerted for that purpose, it opposes the inertia, and the friction of a solid body of the same bearing surface and having the some Weight.

Fourth. Itwill ascend an inclined plane of any angle where the earth will not slide.

Fifth. It will move ov`e`1` obstacles whose abrupt height does not exceed the radius of the curve formed at the en d of the frames or runners. i

Sixth. It will not bury itself, because the force is exerted in a plane parallel to the line of direction; hence, if by standing still on soft ground it should sink, the operation ofk the machine would be to draw itself out of the hole and not to bury itself deeper, as is the case with ordinary machines in siinilur circumstances.

Seventh. The adoption of my machine obviates deep cuts, high embfmkinents, and bridges and tunnels, at least, to e great extent, because it possesses the power of ascending heavier grades than spossihle at present Eighth. The construction ofthe machine enables it to run equally Well either backward or for\\ard,ivholly obviating the.necessity of turning, and the consequent loss of time.

Ninth. It forms aperfect power for agricultural purposes, as it will do all the work of al horse sind co'npress the earth less, and cnn be easily constructed to act as a stationary engine at the same time.

Tenth. It can be turned completely round, when so desired, in the smallest possiblevspece, by simply causing the bands to move in opposite directions.

Having thus described my invention, what I claim as new', und desire tosecure by Letters Patent, is

The grooved rollers B and ribbed bend C, in combination with the curved end frtme A, bearing the working parts, which communicate motion to the band, constructed and applied as described for the purpose specified.

The above specification of my invention signed by me this 28th day of March, 1866.

. R. J. NUNN.

Witnesses:

JOHN M. GARRARD, WM. D. HARDBN. 

